We have experimentally found a correlation between the nonlinear characteristics of frequency-doubling optical fibers and a specific modification of their Raman spectra. We propose a tentative interpretation of the physical origin of these phenomena, based on the assumption of the existence of small Si—O rings inside the fiber material. These structures would explain the nonzero value of the second-order nonlinear susceptibility.
© 1987 Optical Society of America
J. M. Gabriagues and H. Février, "Analysis of frequency-doubling processes in optical fibers using Raman spectroscopy," Opt. Lett. 12, 720-722 (1987)